Feb. 28, 2013 at 6:21 PM ET
The commercial SpaceX rocket venture says it's resolved the problems that cropped up during last October's cargo run to the International Space Station, and all systems are go for the delivery mission due for launch on Friday.
"We're a launch company," SpaceX President Gwynne Shotwell said during a pre-launch briefing at NASA's Kennedy Space Center in Florida on Thursday. "We love to launch."
SpaceX's Falcon 9 rocket is due to lift off from Space Launch Complex 40 at Cape Canaveral Air Force Station at 10:10 a.m. ET Friday. Forecasters said there was an 80 percent chance of acceptable weather for an on-time launch, with only a minor concern about the potential for thick cloud cover.
This will mark the third launch of an unmanned SpaceX Dragon cargo capsule to the space station. It's the second cargo delivery under the terms of a $1.6 billion, 12-flight resupply contract with NASA. And it's the first time that a payload has been carried in the Dragon's unpressurized "trunk."
The trunk is an extra cargo space sitting beneath the Dragon's pressurized main compartment. It's basically been empty for the Dragon's previous two launches, in May and October 2012, but this time there'll be an 822-pound (373-kilogram) package containing a new set of grapple bars to be installed onto the station during a later spacewalk. The package will be put into storage using the station's robotic arm during the three weeks that the Dragon is due to be hooked up to the orbital outpost.
Another 1,493 pounds (677 kilograms) will be riding in the pressurized space, Shotwell said. That cargo will include food, clothing and other crew provisions as well as scientific experiments, two freezers for lab samples and spare parts for the station's air-scrubbing system. Unlike last time, there'll won't be any satellites flying as a secondary payload on the Dragon, Shotwell said.
In October, the previous Dragon mission failed to deploy its secondary payload, an Orbcomm communications satellite, because of an engine problem that occurred during the Falcon 9's ascent. Shotwell said the problem was traced to "a material flaw that went undetected" in the sheathing around one of the nine Merlin engines on the Falcon's first stage. The failure of that material resulted in a breach that caused the engine to lose pressure, signaling the rocket's flight computer to shut down the engine.
Despite the engine shutdown, the rocket was able to reach the required altitude for the space station delivery. It couldn't deliver the Orbcomm OG2 satellite to its proper orbit, however. Days later, the satellite fell out of the sky.
Shotwell said the engine assembly for the rocket to be launched on Friday has gone through extensive testing, using a procedure called non-destructive evaluation, or NDE. She said half-jokingly that engineers skilled in NDE procedures were more valued in the wake of last October's anomaly. "We're hiring you at SpaceX," she said.
She also discussed another anomaly that came to light after the previous Dragon's splashdown: The spacecraft sat in Pacific waters off the coast of California for hours, and it turned out that the water may have shorted out the power supply for the research freezer shipped down from the space station. NASA space station manager Mike Suffredini told reporters that the freezer was "fine, even with the loss of power." Since then, the Dragon for Friday's mission has been retrofitted to make the power supply more watertight, Shotwell said.
Suffredini said he was satisfied with the way that SpaceX followed up on the anomalies. "There's nothing that we would have done that they have chosen not to do," he said.
NASA has had its own share of problems crop up: Last week, the space station's main communication system went out for several hours during a software upgrade, but Suffredini said the outage "was never really a big concern." The software was eventually upgraded successfully, he said.
"Over a million lines of code were upgraded, including the software for the [robotic] arm that's going to capture the Dragon," Suffredini said.
A fast flight
The flight plan calls for the Falcon 9 to send the Dragon capsule on an orbital trajectory that will bring it to the station less than 24 hours after launch. That's a significant faster trip than the previous Dragon flights, due to a favorable orbital geometry, Shotwell said. When the Dragon comes within 10 meters (33 feet), astronauts will use the station's robotic arm to latch onto the spacecraft and pull it in for its berthing at a port on the Harmony module. The hatch would be opened on Sunday. Then the astronauts would unload the supplies and fill the Dragon back up with cargo to be returned to Earth.
The Dragon is due to be unberthed on March 25, and will head down to a Pacific splashdown and recovery.
SpaceX's cargo flights are meant to fill the gap left by the retirement of NASA's space shuttle fleet in 2011. Another company, Orbital Science Corp., has a separate NASA contract to begin deliveries to the space station later this year. Cargo can also be delivered to the space station on Russian, Japanese and European transports, but only SpaceX currently has the capability to bring cargo back down.
SpaceX and two other companies, Sierra Nevada Corp. and the Boeing Co., are developing crew-capable spacecraft under a separate NASA program. Those spaceships could be ready for NASA's use as early as 2017. In the meantime, U.S. astronauts have to ride on Russian Soyuz capsules at a cost of about $60 million per seat.
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Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.